Apparatus and method for supporting tubes



Aug. 23, 1966 J UH APPARATUS AND METHOD FOR SUPPORTING TUBES Filed Aug. 4, 1964 FIG.5

INVENT OR. JAKOB BRUHL AGENT United States, Patent 3,267,913 ATPARATUS AND METHOD FOR SUPPORTING TUBES Jakob Briihl, Suessen, Germany, assignor to Kohlenscheidungs-Gesellschaft m.b.H., a corporation of German y Filed Aug. 4, 1964, Ser. No. 387,359 Claims priority, application Germany, Aug. 9, 1963,

. K 50,473 3 Claims. (Cl. 122-510) The invention relates to an apparatus and method for supporting tubular heating surfaces located in a vertical combustion gas pass. More particularly, the invention relates to suspending the tube panels of the convection heating surface of a steam generator from the roof of the rear pass thereof.

In steam generators having a rear downflow gas pass it is customary to support on hanger tubes the horizontal tube legs of the tube panels located in the rear pass, with these hanger tubes being cooled by the working medium flowing therethrough. Two types of supports have found general application. One support consists of resting the horizontal portion of the panel tubes on brackets that are protruding from and welded to the sides of the hanger tubes. And the other support consists in attaching the tubes of the tube panels to the hanger tubes by means of U-straps surrounding the panel tubes and with the U- straps being welded to the hanger tubes.

Both methods are comparatively expensive to fabricate. Above all, they are not suitable for use with heat exchangers which are located in the high temperature zone of steam generators burning a fuel such as oil, which produces combustion gases causing corrosion of steel parts at highly elevated temperatures. The brackets as well as the U-straps are cooled by the working medium flowing through the tube panels as well as through the hanger tubes. This cooling is sufficient to prevent destruction of the support elements by burning. However, the temperature of these supports usually attains such a high level during operation of the unit that the support elements are subject to the above high temperature corrosion damage caused by the combustion gases that are pro-.

duced when firing commercial fuel oil, forexample.

In accordance with the invention a tube support is disclosed which is not only suitable for general application, but which avoids the above disadvantages of conventional supports with. respect to high temperature corrosion. This is accomplished by utilizing finned hanger tubes, with the fins thereof being provided with cut-outs or notches conforming to the shape of the panel tubes, and with the panel tubes being welded to the fins within the area of the notched-out surface. For this design, commercially available finned tubes preferably are employed which are provided with fins made of a material that possesses a favorably high heat transfer coefficient. The fins serving as supporting element for the panel tubes are therefore cooled to such a high degree that high temperature corrosion cannot take place.

An additional advantage of the invention is achieved by the fact that a direct weld to the wall of the hanger tube is avoided. Such weld generally would reduce the load carrying capacity of the hanger tube.

Accordingly, it is an object of the invention to provide a hanger support for the heating surface disposed in the high temperature zone of a steam generator, which support is of such design that the cooling of the support elements such as tube fins by the working fluid lowers the temperature thereof sufiiciently to prevent high temperature corrosion of the support elements.

Other objects and advantages of the invention will become apparent from the following description of an Patented August 23, 1966 illustrative embodiment thereof when taken in conjunction with the accompanying drawings wherein:

FIG. 1 is a diagrammatic longitudinal section through a steam generator;

SIG. 2 is a partial section taken on line 22 of FIG. 1; an

FIG. 3 is a section taken on line 3-3 of FIG. 2.

Referring now to the drawings wherein like reference characters are used throughout to designate like elements, the illustrative and preferred embodiment of the invention depicted therein includes a vapor generator designated generally as 10 and comprising a vertical cyclone furnace 12 and a radiation chamber 14 both lined with water carrying tubes 16, a steam and water drum 18, a radiant superheater 20, a convection superheater 22, an economizer heating surface 23 and an air heater 24 located in a rear boiler pass 25.

Fuel and air is introduced into thecyclone furnace 12 by way of duct 26 and burners 27, with the air having been preheated in air heater 24. The gases generated in the cyclone chamber 12 flow upwardly through radiation chamber 14 giving off heat to the tubes 16 lining the furnace chambers 12 and 14. The gases then pass successively over heating surfaces 20, 22, 23 and 24 and are discharged into the atmosphere by way of a stack, not shown. Feedwater enters economizer 23 by Way of feed pipe 28 and hanger tubes 29. The water after having been preheated in economizer 23 flows into drum 18 by way of tubes 30. Downcomers 32 deliver the water to headers 34 from which the water rises in tubes 16. Steam is generated in furnace tubes 16 and discharged in a mixture of steam and water into drum 18. Separation of water and steam takes place in drum 18 with the steam passing to convection superheater 22 and radiant superheater 20, from whence the superheated steam is being delivered by way of conduit 38 to a point of use, not shown.

The economizer 23 arranged in the rear pass of the boiler comprises a multiplicity of tube coils 39 spacedly arranged across the width of the rear pass 25. These coils consist of sinuously formed tubes having parallel tube legs 40, with the tubes of one tube coil preferably being oifset with respect to the tubes of the adjacent tube coils. Two hanger tubes 42 are arranged between two adjacent tube coils 39. These hanger tubes 42 are provided with fins 44 which face the tube coils 39. These fins 44 are of such design that the working fluid passing through the hanger tube 42 lowers the temperature of fin 44 sufiiciently to prevent high temperature corrosion of fin 44. The hanger tubes 42 are supported from the roof of the boiler by conventional supports, not shown. Notches or cut-outs 46 are provided in the fins 44 of hanger tube 42, with these cut-outs 46 conforming to the shape of the horizontal tube leg 40, and with the tube leg 40 welded to the fins 44 Within the area of the notched-out surface 46. In most cases it is sufficient to merely tack weld the tube legs 40 to the fins 44 preferably within the upper surface of the cut-outs 46.

While I have illustrated and described a preferred embodiment of my invention, it is to be understood that such is merely illustrative and not restrictive and that variations and modifications may be made therein without departing from the spirit and scope of the invention. I therefore do not wish to be limited to the precise details set forth but desire to avail myself of such changes as fall within the purview of my invention.

I claim:

1. In a heat exchanger having an elongated gas pass for flow of heating gases therethrough, in combination a bank of upright parallelly spaced tubular coils suspended in said gas pass, each coil comprising a multiplicity of vertically spaced tubes; supporting means for said coils comprising a fluid cooled hanger tube positioned between said tubular coils; at least one continuous longitudinal fin projecting from said hanger tube and facing said vertically spaced tubes and extending throughout the height of said coils, said fin having a width Within the cooling range of said hanger tube to prevent high temperature corrosion of said fin; said fin being provided with cutouts to fit the contour of said vertically spaced tubes, said cut-outs being of a depth penetrating the major portion of the width of said fin; and a Weld applied to said fin only and to said vertically spaced tubes within the extent of said cut-outs and without employing a direct Weld to the body of said hanger tube.

2. In a heat exchanger having an elongated gas pass for flow of heating gases therethrough, in combination a bank of upright parallelly spaced tubular coils suspended in said gas pass, each coil comprising a multiplicity of vertically spaced tubes; supporting means for said coils comprising a fluid cooled hanger tube positioned between at least two of said tubular coils; a continuous longitudinal fin projecting from each of two opposite sides of said hanger tube and facing said vertically spaced tubes and extending throughout the height of said coils said fin having a width within the cooling range of said hanger tube to prevent high temperature corrosion of said fin; said fin being provided with cut-outs to fit the contour of said vertically spaced tubes, said cut-outs being of a depth penetrating the major portion of said 30 fin; and a Weld applied only to said fin and to said vertically spaced tubes Within the extent of said cut-outs, and

without employing a direct weld to the body of said hanger tube.

3. In a heat exchanger, the method of supporting the sinuously arranged and horizontal tube legs of an upright tube coil by means of hanger tubes, comprising the steps of:

suspending vertically from an overhead support and adjacent to said upright tube coil a continuously finned fluid cooled hanger tube with the fin facing said tube coil, said fin having a width Within the cooling range of said hanger tube to prevent high temperature corrosion of said fin;

cutting notches into said fin at the location of and in conformity with the contour of said tube legs to provide a cradle for each tube leg and of a depth which penetrates the major portion of the width of said fin; and

welding the tube legs to the fin only Within the area of contact between said tube coil and said notchedout surface and without employing a direct weld to the body of said hanger tube.

References fitted by the Examiner UNITED STATES PATENTS 2,893,698 7/1959 Nunninghoif 165-462 XR FOREIGN PATENTS 771,052 7/1934 France. 890,652 9/1953 Germany.

KENNETH W. SPRA-GUE, Primary Examiner. 

1. IN A HEAT EXCHANGER HAVING AN ELONGATED GAS PASS FOR FLOW OF HEATING GASES THERETHROUGH, IN COMBINATION A BANK OF UPRIGHT PARALLELLY SPACED TUBULAR COILS SUSPENDED IN SAID GAS PASS, EACH COIL COMPRISING A MULTIPLICITY OF VERTICALLY SPACED TUBES; SUPPORTING MEANS FOR SAID COILS COMPRISING A FLUID COOLED HANGER TUBE POSITIONED BETWEEN SAID TUBULAR COILS; AT LEAST ONE CONTINUOUS LONGITUDINAL FIN PROJECTING FROM SAID HANGER TUBE AND FACING SAID VERTICALLY SPACED TUBES AND EXTENDING THROUGHOUT THE HEIGHT OF SAID COILS, SAID FIN HAVING A WIDTH WITHIN THE COOLING RANGE OF SAID HANGER TUBE TO PREVENT HIGH TEMPERATURE CORROSION OF SAID FIN; SAID FIN BEING PROVIDED WITH CUTOUTS TO FIT THE CONTOUR OF SAID VERTICALLY SPACED TUBES, SAID CUT-OUTS BEING OF A DEPTH PENETRATING THE MAJOR PORTION OF THE WIDTH OF SAID FIN; AND A WELD APPLIED TO SAID FIN ONLY AND TO SAID VERTICALLY SPACED TUBES WITHIN THE EXTEND OF SAID CUT-OUTS AND WITHOUT EMPLOYING A DIRECT WELD TO THE BODY OF SAID HANGER TUBE. 